Hello!
On one hand it is a name based on what you don't believe in, which is a very uncommon way of identifying things, by what they aren't.
I have to disagree with you there. You are mixing agnosticism with atheism there. Atheism means that you believe in the non-existence of any gods/divine beings. It does not refer to the other options but rather states clearly what you believe in: a completely mundane world.
Secondly, religion is based on faith, atheism isn't.
Once you have found a way to disprove the existence of divinity
without using axioms inherent of atheism, your statement would be correct. But as it stands, atheism requires just as much faith as religion. Atheists
believe there is no divinity, just as much as Christians
believe in the existence of the Christian god, and neither side has any better proof for their belief than the other side.
Whether to classify atheism as a religion or not is a very difficult question. In many regards, atheism works as a religion, in other regards it can not do so. For instance, atheism answers the same questions about the creation of the world, the creation of humanity. It also answers the question of meaning.
In addition, it definitely takes up the same slot as theist religions. That is, if you are an atheist, you can't be a Christian.
On the other hand, atheism lacks rituals and community, and more importantly, it inherently denies objective ethics, thus providing no ethics in and of itself.
Personally, I prefer to refer to atheism as a religion, simply as this stresses that atheists are just as dependent on faith as theist people. The atheist position is in no way objectively superior or inferior to the theist position in that regard, and this is something important too many people tend to forget.
Yours,
Deathworks